Radiofrequency Identification (RFID) systems are widely used in many different applications. For example, RFID systems that include associated readers allow individuals to access buildings and electronic services (such as arming and disarming alarm systems) using an RFID card associated with that individual that may be read by the RFID reader.
As the use of RFID systems increases and the design of the card readers becomes more compact, including smaller and thinner readers, the impact to performance of these readers from environmental influences will likely increase. For example, card readers will likely be installed in many different locations and on many different types of surfaces, such as on walls of a building, on wooden door frames and on conducted wall surfaces, among other surfaces. While non-conducting surfaces, such as wood and stone, on which these RFID readers may be mounted do not affect the performance of the readers, when the readers are mounted on conducting surfaces, such as surfaces that include metal (e.g., copper or aluminum), the performance of the readers can be adversely affected. In particular, conducted surfaces, such as copper, aluminum or steel can have a negative impact on the magnetic field distribution of the card reader antenna. This negative impact can result in, for example, decreased card reader detection range. Thus, these card readers do not always provide acceptable performance independent of the nature of the surface on which the card readers are mounted.